Mike Arrington's TechCrunch has posted a series of articles on the issue of sleazy revenue models for online games, exposing the practice of sneaking mobile data subscriptions and pricey "learning CD" packages past players trying to earn online "points." Mafia Wars and Farmville creator Zynga gets a third of its revenue from such "commercial offers," while Facebook in turn gets 10-20 percent of its money from Zynga, according to Arrington.